Imaging lens and electronic apparatus including the same

ABSTRACT

An imaging lens includes first to fifth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant lens parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Patent Application No.103138532, filed on Nov. 6, 2014.

FIELD OF INVENTION

The invention relates to an imaging lens and an electronic apparatusincluding the same.

BACKGROUND OF THE INVENTION

In recent years, as portable electronic devices (e.g., mobile phones anddigital cameras) become ubiquitous, much effort has been put intoreducing dimensions of portable electronic devices. Moreover, asdimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, dimensions ofimaging lenses for use with the optical sensors must be correspondinglyreduced without significantly compromising optical performance. However,the most important characteristics of imaging lenses are imaging qualityand size.

U.S. Pat. No. 8,441,736 discloses a relatively long conventional imaginglens that includes five lens elements and that has a system length whichcannot be effectively reduced to a certain length. This configurationrenders the same unsuitable to be incorporated into a mobile phone witha thin design.

Therefore, greater technical difficulties are encountered for aminiaturized imaging lens than for traditional imaging lenses. Producingan imaging lens that meets requirements of consumer electronic productswhile having satisfactory optical performance is always a goal in theindustry.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide an imaginglens having a shorter overall length while maintaining good opticalperformance.

According to one aspect of the present invention, there is provided animaging lens including a first lens element, an aperture stop, a secondlens element, a third lens element, a fourth lens element and a fifthlens element arranged in order from an object side to an image sidealong an optical axis of the imaging lens. Each of the first lenselement, the second lens element, the third lens element, the fourthlens element and the fifth lens element has a refractive power, anobject-side surface facing toward the object side, and an image-sidesurface facing toward the image side.

The image-side surface of the first lens element has a concave portionin a vicinity of a periphery of the first lens element. The object-sidesurface of the second lens element has a convex portion in a vicinity ofa periphery of the second lens element, and the image-side surface ofthe second lens element has a convex portion in a vicinity of theperiphery of the second lens element. The third lens element is made ofa plastic material. The image-side surface of the fourth lens elementhas a convex portion in a vicinity of a periphery of the fourth lenselement. The object-side surface of the fifth lens element has a concaveportion in a vicinity of a periphery of the fifth lens element.

The imaging lens satisfies (G12+G45)/T3≧1.5 and T3/G12≦1.1, where G12represents an air gap length between the first lens element and thesecond lens element at the optical axis, G45 represents an air gaplength between the fourth lens element and the fifth lens element at theoptical axis, and T3 represents a thickness of the third lens element atthe optical axis.

Another object of the present invention is to provide an electronicapparatus including an imaging lens with five lens elements.

According to another aspect of the present invention, there is providedan electronic apparatus including a housing and an imaging module. Theimaging module is disposed in the housing, and includes the imaging lensof this invention, a barrel on which the imaging lens is disposed, aholder unit on which the barrel is disposed, and an image sensordisposed at the image side of the imaging lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the embodiments withreference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram to illustrate surface shape and structureof a lens element;

FIG. 2 is a schematic diagram to illustrate concave and convex portionsand a focal point of a lens element;

FIG. 3 is a schematic diagram to illustrate surface shape and structureof a first exemplary lens element;

FIG. 4 is a schematic diagram to illustrate surface shape and structureof a second exemplary lens element;

FIG. 5 is a schematic diagram to illustrate surface shape and structureof a third exemplary lens element;

FIG. 6 is a schematic diagram that illustrates the first embodiment ofan imaging lens according to the present disclosure;

FIG. 7 shows values of some optical data corresponding to the imaginglens of the first embodiment;

FIG. 8 shows values of some aspherical coefficients corresponding to theimaging lens of the first embodiment;

FIGS. 9(A) to 9(D) show different optical characteristics of the imaginglens of the first embodiment;

FIG. 10 is a schematic diagram that illustrates the second embodiment ofan imaging lens according to the present disclosure;

FIG. 11 shows values of some optical data corresponding to the imaginglens of the second embodiment;

FIG. 12 shows values of some aspherical coefficients corresponding tothe imaging lens of the second embodiment;

FIGS. 13(A) to 13(D) show different optical characteristics of theimaging lens of the second embodiment;

FIG. 14 is a schematic diagram that illustrates the third embodiment ofan imaging lens according to the present disclosure;

FIG. 15 shows values of some optical data corresponding to the imaginglens of the third embodiment;

FIG. 16 shows values of some aspherical coefficients corresponding tothe imaging lens of the third embodiment;

FIGS. 17(A) to 17(D) show different optical characteristics of theimaging lens of the third embodiment;

FIG. 18 is a schematic diagram that illustrates the fourth embodiment ofan imaging lens according to the present disclosure;

FIG. 19 shows values of some optical data corresponding to the imaginglens of the fourth embodiment;

FIG. 20 shows values of some aspherical coefficients corresponding tothe imaging lens of the fourth embodiment;

FIGS. 21(A) to 21(D) show different optical characteristics of theimaging lens of the fourth embodiment;

FIG. 22 is a schematic diagram that illustrates the fifth embodiment ofan imaging lens according to the present disclosure;

FIG. 23 shows values of some optical data corresponding to the imaginglens of the fifth embodiment;

FIG. 24 shows values of some aspherical coefficients corresponding tothe imaging lens of the fifth embodiment;

FIGS. 25(A) to 25(D) show different optical characteristics of theimaging lens of the fifth embodiment;

FIG. 26 is a schematic diagram that illustrates the sixth embodiment ofan imaging lens according to the present disclosure;

FIG. 27 shows values of some optical data corresponding to the imaginglens of the sixth embodiment;

FIG. 28 shows values of some aspherical coefficients corresponding tothe imaging lens of the sixth embodiment;

FIGS. 29(A) to 29(D) show different optical characteristics of theimaging lens of the sixth embodiment;

FIGS. 30 and 31 are tables that list values of relationships among somelens parameters corresponding to the imaging lenses of the first tosixth embodiments;

FIG. 32 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present disclosure; and

FIG. 33 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

In the present specification, the description “a lens element havingpositive refracting power (or negative refracting power)” means that theparaxial refracting power of the lens element in Gaussian optics ispositive (or negative). The description “An object-side (or image-side)surface of a lens element” only includes a specific region of thatsurface of the lens element through which imaging rays are capable ofpassing, namely the clear aperture of the surface. The aforementionedimaging rays can be classified into two types, chief rays (Lc) andmarginal rays (Lm). Taking a lens element depicted in FIG. 1 as anexample, the lens element is rotationally symmetric, where the opticalaxis (I) is the axis of symmetry. The region (A) of the lens element isdefined as “a portion in a vicinity of the optical axis (I)”, and theregion (C) of the lens element is defined as “a portion in a vicinity ofa periphery of the lens element”. Besides, the lens element may alsohave an extending portion (E) extended radially and outwardly from theregion (C), namely the portion outside of the clear aperture of the lenselement. The extending portion (E) is usually used for physicallyassembling the lens element into an optical imaging lens system. Undernormal circumstances, the imaging rays would not pass through theextending portion (E) and only pass through the clear aperture. Thestructures and shapes of the aforementioned extending portion (E) areonly examples for technical explanation, and the structures and shapesof lens elements should not be limited to these examples. Note that theextending portions of the lens element surfaces depicted in thefollowing embodiments are partially omitted.

The following criteria are provided for determining the shapes and theportions of lens element surfaces set forth in the presentspecification. These criteria mainly determine the boundaries ofportions under various circumstances including the portion in thevicinity of the optical axis (I), the portion in the vicinity of theperiphery of a lens element surface, and other types of lens elementsurfaces such as those having multiple portions.

1. FIG. 1 is a radial cross-sectional view of a lens element. Beforedetermining boundaries of those aforesaid portions, two referentialpoints should be defined first, central point and transition point. Thecentral point of a surface of a lens element is a point of intersectionof that surface and the optical axis (I). The transition point is apoint on a surface of a lens element, where the tangent line of thatpoint is perpendicular to the optical axis (I). Additionally, ifmultiple transition points appear on one single surface, then thesetransition points are sequentially named along the radial direction ofthe surface with numbers starting from the first transition point. Forinstance, these transition points may be the first transition point(closest one to the optical axis (I)), the second transition point, . .. and the N^(th) transition point (the farthest one from the opticalaxis (I) within the scope of the clear aperture of the surface). Theportion of a surface of a lens element between the central point and thefirst transition point is defined as the portion in the vicinity of theoptical axis (I). The portion located radially outside of the N^(th)transition point (but still within the scope of the clear aperture) isdefined as the portion in the vicinity of the periphery of the lenselement. In some embodiments, there are other portions existing betweenthe portion in the vicinity of the optical axis (I) and the portion inthe vicinity of the periphery of the lens element; the number ofportions depend on the number of the transition point (s). In addition,the radius of the clear aperture (or a so-called effective radius) of asurface is defined as the radial distance from the optical axis (I) to apoint of intersection of the marginal ray (Lm) and the surface of thelens element.

2. Referring to FIG. 2, determining whether the shape of a portion isconvex or concave depends on whether a collimated ray passing throughthat portion converges or diverges. That is, while applying a collimatedray to a portion to be determined in terms of shape, the collimated raypassing through that portion will be bent and the ray itself or itsextension line will eventually meet the optical axis (I). The shape ofthat portion can be determined by whether the ray or its extension linemeets (intersects) the optical axis (I) (focal point) at the object-sideor image-side. For instance, if the ray itself intersects the opticalaxis (I) at the image side of the lens element after passing through aportion, i.e., the focal point of this ray is at the image side (seepoint R in FIG. 2), the portion will be determined as having a convexshape. On the contrary, if the ray diverges after passing through aportion, and the extension line of the ray intersects the optical axis(I) at the object side of the lens element, i.e., the focal point of theray is at the object side (see point (M) in FIG. 2), that portion willbe determined as having a concave shape. Therefore, referring to FIG. 2,the portion between the central point and the first transition point hasa convex shape, the portion located radially outside of the firsttransition point has a concave shape, and the first transition point isthe point where the portion having a convex shape changes to the portionhaving a concave shape, namely the border of two adjacent portions.Alternatively, there is another common way for a person with ordinaryskill in the art to tell whether a portion in a vicinity of the opticalaxis has a convex or concave shape by referring to the sign of an “R”value, which is the (paraxial) radius of curvature of a lens surface.The R value is commonly used in conventional optical design softwaresuch as Zemax and CodeV. The R value usually appears in the lens datasheet in the software. For an object-side surface, positive R means thatthe object-side surface is convex, and negative R means that theobject-side surface is concave. Conversely, for an image-side surface,positive R means that the image-side surface is concave, and negative Rmeans that the image-side surface is convex. The result found by usingthis method should be consistent with that by using the other waymentioned above, which determines surface shapes by referring to whetherthe focal point of a collimated ray is at the object side or the imageside.

3. For none transition point cases, the portion in the vicinity of theoptical axis is defined as the portion between 0˜50% of the effectiveradius (radius of the clear aperture) of the surface, whereas theportion in the vicinity of the periphery of the lens element is definedas the portion between 50˜1000 of the effective radius (the radius ofthe clear aperture) of the surface.

Referring to the first example depicted in FIG. 3, only one transitionpoint, namely a first trans it ion point, appears within the clearaperture of the image-side surface of the lens element. Portion (i) is aportion in the vicinity of the optical axis, and portion (ii) is aportion in the vicinity of the periphery of the lens element. Theportion in the vicinity of the optical axis (I) is determined as havinga concave surface due to the R value at the image-side surface of thelens element being positive. The shape of the portion in the vicinity ofthe periphery of the lens element is different from that of the radiallyinner adjacent portion, i.e., the shape of the portion in the vicinityof the periphery of the lens element is different from the shape of theportion in the vicinity of the optical axis (I); the portion in thevicinity of the periphery of the lens element has a convex shape.

Referring to the second example depicted in FIG. 4, a first transitionpoint and a second transition point exist on the object-side surface(within the clear aperture) of a lens element. In the second example,portion (i) is the portion in the vicinity of the optical axis (I), andportion (iii) is the portion in the vicinity of the periphery of thelens element. The portion in the vicinity of the optical axis (I) has aconvex shape because the R value at the object-side surface of the lenselement is positive. The portion in the vicinity of the periphery of thelens element (portion iii) has a convex shape. Furthermore, there isanother portion having a concave shape existing between the first andsecond transition points (portion (ii)).

Referring to a third example depicted in FIG. 5, no transition pointexists on the object-side surface of the lens element. In this case, theportion between 0˜50% of the effective radius (the radius of the clearaperture) is determined as the portion in the vicinity of the opticalaxis (I), and the portion between 50˜100% of the effective radius isdetermined as the portion in the vicinity of the periphery of the lenselement. The portion in the vicinity of the optical axis (I) of theobject-side surface of the lens element is determined as having a convexshape due to its positive R value, and the portion in the vicinity ofthe periphery of the lens element is determined as having a convex shapeas well.

Referring to FIG. 6, the first embodiment of an imaging lens 10according to the present disclosure includes a first lens element 3, anaperture stop 2, a second lens element 4, a third lens element 5, afourth lens element 6, a fifth lens element 7 and an optical filter 9arranged in the given order from an object side to an image side alongan optical axis (I) of the imaging lens 10. The optical filter 9 is aninfrared cut filter for selectively absorbing infrared light to therebyreduce imperfection of images formed at an image plane 100.

Each of the first, second, third, fourth and fifth lens elements 3-7 andthe optical filter 9 has an object-side surface 31, 41, 51, 61, 71, 91facing toward the object side, and an image-side surface 32, 42, 52, 62,72, 92 facing toward the image side. Light entering the imaging lens 10travels through the object-side and image-side surfaces 31, 32 of thefirst lens element 3, the aperture stop 2, the object-side andimage-side surfaces 41, 42 of the second lens element 4, the object-sideand image-side surfaces 51, 52 of the third lens element 5, theobject-side and image-side surfaces 61, 62 of the fourth lens element 6,the object-side and image-side surfaces 71, 72 of the fifth lens element7, and the object-side and image-side surfaces 91, 92 of the opticalfilter 9, in the given order, to form an image on the image plane 100.In this embodiment, each of the object-side surfaces 31, 41, 51, 61, 71,and the image-side surfaces 32, 42, 52, 62, 72, is aspherical and has acenter point coinciding with the optical axis (I).

Each of the lens elements 3-7 is made of a plastic material and has arefractive power in this embodiment. However, at least one of the lenselements 3, 4, 6 and 7 may be made of other materials in otherembodiments.

In the first embodiment, which is depicted in FIG. 6, the first lenselement 3 has a negative refractive power. The object-side surface 31 ofthe first lens element 3 is a convex surface that has a convex portion311 in a vicinity of the optical axis (I), and a convex portion 312 in avicinity of a periphery of the first lens element 3. The image-sidesurface 32 of the first lens element 3 is a concave surface that has aconcave portion 321 in a vicinity of the optical axis (I), and a concaveportion 322 in a vicinity of the periphery of the first lens element 3.

The second lens element 4 has a positive refractive power. Theobject-side surface 41 of the second lens element 4 is a convex surfacethat has a convex portion 411 in a vicinity of the optical axis (I), anda convex portion 412 in a vicinity of a periphery of the second lenselement 4. The image-side surface 42 of the second lens element 4 is aconvex surface that has a convex portion 421 in a vicinity of theoptical axis (I), and a convex portion 422 in a vicinity of theperiphery of the second lens element 4.

The third lens element 5 has a negative refractive power. Theobject-side surface 51 of the third lens element 5 is a concave surfacethat has a concave portion 511 in a vicinity of the optical axis (I),and a concave portion 512 in a vicinity of a periphery of the third lenselement 5. The image-side surface 52 of the third lens element 5 has aconcave portion 521 in a vicinity of the optical axis (I), and a convexportion 522 in a vicinity of the periphery of the third lens element 5.

The fourth lens element 6 has a positive refractive power. Theobject-side surface 61 of the fourth lens element 6 is a concave surfacethat has a concave portion 611 in a vicinity of the optical axis (I),and a concave portion 612 in a vicinity of a periphery of the fourthlens element 6. The image-side surface 62 of the fourth lens element 6is a convex surface that has a convex portion 621 in a vicinity of theoptical axis (I), and a convex portion 622 in a vicinity of theperiphery of the fourth lens element 6.

The fifth lens element 7 has a negative refractive power. Theobject-side surface 71 of the fifth lens element 7 has a convex portion711 in a vicinity of the optical axis (I), and a concave portion 712 ina vicinity of a periphery of the fifth lens element 7. The image-sidesurface 72 of the fifth lens element 7 has a concave portion 721 in avicinity of the optical axis (I), and a convex portion 722 in a vicinityof the periphery of the fifth lens element 7.

In the first embodiment, the imaging lens 10 does not include any lenselement with refractive power other than the aforesaid lens elements3-7.

Shown in FIG. 7 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92, of thefirst embodiment. The imaging lens 10 has an overall system effectivefocal length (EFL) of 2.3899 mm, a half field-of-view (HFOV) of42.9762°, an F-number of 2.2, and a system length of 4.135 mm. Thesystem length refers to a distance between the object-side surface 31 ofthe first lens element 3 and the image plane 100 at the optical axis(I).

In this embodiment, each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 is aspherical, and satisfies the relationshipof

$\begin{matrix}{{Z(Y)} = {{\frac{Y^{2}}{R}/\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}{a_{2i} \times Y^{2i}}}}} & (1)\end{matrix}$

where:

R represents a radius of curvature of an aspherical surface;

Z represents a depth of the aspherical surface, which is defined as aperpendicular distance between an arbitrary point on the asphericalsurface that is spaced apart from the optical axis (I) by a distance Y,and a tangent plane at a vertex of the aspherical surface at the opticalaxis (I);

Y represents a perpendicular distance between the arbitrary point on theaspherical surface and the optical axis (I);

K represents a conic constant; and

a_(2i) represents a 2i^(th) aspherical coefficient.

Shown in FIG. 8 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefirst embodiment. Each of the columns numbered 31-71 and 32-72 in FIG. 8lists the aspherical coefficients of a respective one of the object-sidesurfaces 31-71 and the image-side surfaces 32-72.

Relationships among some of the lens parameters corresponding to thefirst embodiment are shown in FIGS. 30 and 31. Note that someterminologies are defined as follows:

T1 represents a thickness of the first lens element 3 at the opticalaxis (I);

T2 represents a thickness of the second lens element 4 at the opticalaxis (I);

T3 represents a thickness of the third lens element 5 at the opticalaxis (I);

T4 represents a thickness of the fourth lens element 6 at the opticalaxis (I);

T5 represents a thickness of the fifth lens element 7 at the opticalaxis (I);

G12 represents an air gap length between the first lens element 3 andthe second lens element 4 at the optical axis (I);

G23 represents an air gap length between the second lens element 4 andthe third lens element 5 at the optical axis (I);

G34 represents an air gap length between the third lens element 5 andthe fourth lens element 6 at the optical axis (I);

G45 represents an air gap length between the fourth lens element 6 andthe fifth lens element 7 at the optical axis (I);

Gaa represents a sum of the four air gap lengths among the first lenselement 3, the second lens element 4, the third lens element 5, thefourth lens element 6 and the fifth lens element 7 at the optical axis(I) (i.e., the sum of G12, G23, G34 and G45);

ALT represents a sum of the thicknesses of the first lens element 3, thesecond lens element 4, the third lens element 5, the fourth lens element6 and the fifth lens element 7 at the optical axis (I) (i.e., the sum ofT1, T2, T3, T4 and T5);

TTL represents a distance between the object-side surface 31 of thefirst lens element 3 and the image plane 100 at the optical axis (I);

G5F represents an air gap length between the fifth lens element 7 andthe optical filter 9 at the optical axis (I);

TF represents a thickness of the optical filter 9 at the optical axis(I);

GFP represents an air gap length between the optical filter 9 and theimage plane 100 at the optical axis (I);

BFL represents a distance between the image-side surface 72 of the fifthlens element 7 and the image plane 100 at the optical axis (I);

EFL represents a system focal length of the imaging lens 10;

f1, f2, f3, f4 and f5 respectively represent focal lengths of the first,second, third, fourth and fifth and lens elements 3-7;

n1, n2, n3, n4 and n5 respectively represent refractive indices of thefirst, second, third, fourth and fifth lens elements 3-7; and

υ1, υ2, υ3, υ4 and υ5 respectively represent Abbe numbers of the first,second, third, fourth and fifth lens elements 3-7.

FIGS. 9(A) to 9(D) respectively show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefirst embodiment. In each of the simulation results, curvescorresponding respectively to wavelengths of 470 nm, 555 nm, and 650 nmare shown. It can be understood from FIG. 9(A) that, since each of thecurves corresponding to longitudinal spherical aberration has a focallength at each field of view (indicated by the vertical axis) that fallswithin the range of ±0.05 mm, the first embodiment is able to achieve arelatively low spherical aberration at each of the wavelengths.Furthermore, since the curves at each of the wavelengths of 470 nm, 555nm, and 650 nm are close to each other, the first embodiment has arelatively low chromatic aberration.

It can be understood from FIGS. 9(B) and 9(C) that, since each of thecurves falls within the range of ±0.08 mm of focal length, the firstembodiment has a relatively low optical aberration. Moreover, as shownin FIG. 9(D), since each of the curves corresponding to distortionaberration falls within the range of ±2.5%, the first embodiment is ableto meet requirements in imaging quality of most optical systems. In viewof the above, even with the system length reduced down to 4.135 mm, theimaging lens 10 of the first embodiment is still able to achieve arelatively good optical performance.

FIG. 10 illustrates a second embodiment of an imaging lens 10 accordingto the present disclosure, which has a configuration similar to that ofthe first embodiment and differs in optical data, asphericalcoefficients, and lens parameters of the first, second, third, fourthand fifth lens elements 3-7. It should be noted herein that, in order toclearly illustrate the second embodiment, reference numerals of theconvex and concave portions that are the same as those of the firstembodiment have been omitted in FIG. 10.

Shown in FIG. 11 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92 of thesecond embodiment. The imaging lens 10 has an overall system focallength of 2.4315 mm, an HFOV of 42.5196°, an F-number of 2.2, and asystem length of 4.115 mm.

Shown in FIG. 12 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesecond embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the second embodiment are shown in FIGS. 30 and 31.

FIGS. 13(A) to 13(D) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesecond embodiment. It can be understood from FIGS. 13(A) to 13(D) thatthe second embodiment is able to achieve a relatively good opticalperformance.

Via the aforementioned description, the advantages of the secondembodiment in contrast to the first embodiment are as follows. Theimaging lens 10 of this embodiment has a shorter system length andbetter imaging quality, and is easier to manufacture, providing higheryield.

FIG. 14 illustrates a third embodiment of an imaging lens 10 accordingto the present disclosure, which has a configuration similar to that ofthe first embodiment and differs in optical data, asphericalcoefficients, and lens parameters of the first, second, third, fourthand fifth lens elements 3-7. It should be noted herein that, in order toclearly illustrate the third embodiment, reference numerals of theconvex and concave portions that are the same as those of the firstembodiment have been omitted in FIG. 14.

Shown in FIG. 15 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92 of thethird embodiment. The imaging lens 10 has an overall system focal lengthof 2.3485 mm, an HFOV of 43.5747°, an F-number of 2.2, and a systemlength of 4.342 mm.

Shown in FIG. 16 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thethird embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the third embodiment are shown in FIGS. 30 and 31.

FIGS. 17(A) to 17(D) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thethird embodiment. It can be understood from FIGS. 17(A) to 17(D) thatthe third embodiment is able to achieve a relatively good opticalperformance.

Via the aforementioned description, the advantage of the thirdembodiment in contrast to the first embodiment resides in that: theimaging lens 10 of the third embodiment has a greater HFOV, betterimaging quality and is easier to manufacture, providing higher yield.

FIG. 18 illustrates a fourth embodiment of an imaging lens 10 accordingto the present disclosure, which has a configuration similar to that ofthe first embodiment and differs in optical data, asphericalcoefficients, and lens parameters of the first, second, third, fourthand fifth lens elements 3-7. It should be noted herein that, in order toclearly illustrate the fourth embodiment, reference numerals of theconvex and concave portions that are the same as those of the firstembodiment have been omitted in FIG. 18.

Shown in FIG. 19 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92 of thefourth embodiment. The imaging lens 10 has an overall system focallength of 2.516 mm, an HFOV of 41.7283°, an F-number of 2.2, and asystem length of 4.422 mm.

Shown in FIG. 20 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefourth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fourth embodiment are shown in FIGS. 30 and 31.

FIGS. 21(A) to 21(D) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefourth embodiment. It can be understood from FIGS. 21(A) to 21(D) thatthe fourth embodiment is able to achieve a relatively good opticalperformance.

Via the aforementioned description, the advantage of the fourthembodiment in contrast to the first embodiment is that the imaging lens10 of the fourth embodiment has better imaging quality and is easier tomanufacture, providing higher yield.

FIG. 22 illustrates a fifth embodiment of an imaging lens 10 accordingto the present disclosure, which has a configuration similar to that ofthe first embodiment and differs in optical data, asphericalcoefficients, lens parameters of the first, second, third, fourth andfifth lens elements 3-7, and that the object-side surface 51 of thethird lens element 5 has a convex portion 513 in a vicinity of theoptical axis (I) and a concave portion 512 in a vicinity of theperiphery of the third lens element 5. It should be noted herein that,in order to clearly illustrate the fifth embodiment, reference numeralsof the convex and concave portions that are the same as those of thefirst embodiment have been omitted in FIG. 22.

Shown in FIG. 23 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92 of thefifth embodiment. The imaging lens 10 has an overall system focal lengthof 2.466 mm, an HFOV of 42.2699°, an F-number of 2.2, and a systemlength of 4.386 mm.

Shown in FIG. 24 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thefifth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the fifth embodiment are shown in FIGS. 30 and 31.

FIGS. 25(A) to 25(D) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefifth embodiment. It can be understood from FIGS. 25(A) to 25(D) thatthe fifth embodiment is able to achieve a relatively good opticalperformance.

Via the aforementioned description, the advantage of the fifthembodiment in contrast to the first embodiment is that the imaging lens10 of the fifth embodiment has better imaging quality and is easier tomanufacture, providing higher yield.

FIG. 26 illustrates a sixth embodiment of an imaging lens 10 accordingto the present disclosure, which has a configuration similar to that ofthe first embodiment and differs in optical data, asphericalcoefficients, and lens parameters of the first, second, third, fourthand fifth lens elements 3-7. Moreover, the image-side surface 52 of thethird lens element 5 has a concave portion 521 in a vicinity of theoptical axis (I), a concave portion 523 in a vicinity of the peripheryof the third lens element 5, and a convex portion 524 disposed betweenthe concave portions 521, 523. It should be noted herein that, in orderto clearly illustrate the sixth embodiment, reference numerals of theconvex and concave portions that are the same as those of the firstembodiment have been omitted in FIG. 26.

Shown in FIG. 27 is a table that lists values of some optical datacorresponding to the surfaces 31-71 and 91, and 32-72 and 92 of thesixth embodiment. The imaging lens 10 has an overall system focal lengthof 2.517 mm, an HFOV of 41.6194°, an F-number of 2.2, and a systemlength of 4.365 mm.

Shown in FIG. 28 is a table that lists values of some asphericalcoefficients of the aforementioned relationship (1) corresponding to thesixth embodiment.

Relationships among some of the aforementioned lens parameterscorresponding to the sixth embodiment are shown in FIGS. 30 and 31.

FIGS. 29(A) to 29(D) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesixth embodiment. It can be understood from FIGS. 29(A) to 29(D) thatthe sixth embodiment is able to achieve a relatively good opticalperformance.

Via the aforementioned description, the advantage of the sixthembodiment in contrast to the first embodiment is that the imaging lens10 of the sixth embodiment has better imaging quality and is easier tomanufacture, providing higher yield.

Shown in FIGS. 30 and 31 are tables that list the aforesaidrelationships among some of the aforementioned lens parameterscorresponding to the six embodiments. When the lens parameters of theimaging lens 10 according to this disclosure satisfy the followingrelationships, the optical performance is still relatively good evenwith the reduced system length:

(1) To achieve reduction of the system length of the imaging lens 10,thicknesses of the lens elements and air gap lengths in the imaging lens10 are reduced. However, taking into consideration difficulty ofassembly of the imaging lens 10, the extent to which the air gap lengthsthereamong can be reduced is smaller than the extent to which thethicknesses of the lens elements can be reduced. Thus, (G12+G45)/T3≧1.5,T3/G12≦1.1, T4/G23≦20, T4/G23≦20, T5/G23≦20, (G34+G45)/T1≧0.4,ALT/G23≦60 and/or T1/G45≦10 are recommended, and 1.5≦(G12+G45)/T3≦5,0.3≦T3/G12≦1, 0.8≦T2/G23≦3, 1.5≦T4/G23≦3.2, 0.5≦T5/G23≦1.7,0.5≦(G34+G45)/T1≦1.7, 4.0≦ALT/G23≦10.0 and/or 0.6 T1/G45≦3.0 may bedefined in other embodiments.

(2) With the foregoing, even though the reducible degree of thethicknesses of the lens elements is greater than that of the air gaplengths, the reduction thereof should have limitations. Otherwise, themanufacturing process will be complicated. The imaging lens 10 may havebetter imaging results/effects while having a shorter system length ifthe following condition is satisfied: ALT/Gaa≧1, (G12+G34)/T3≦20 and/or(G12+G45)/T5≦7; and 1.0≦ALT/Gaa≦3.0, 1.5≦(G12+G34)/T3≦4.0 and/or1.0≦(G12+G45)/T5≦3.5 may be defined in other embodiments.

(3) In order to achieve reduction of the system length of the imaginglens 10, EFL of the imaging lens 10 may be designed to be relativelysmaller. While taking into consideration difficulty of assembly of theimaging lens 10, a ratio between EFL and the air gap lengths among thelens elements should be maintained within an appropriate range. Theimaging lens 10 may have better performance if the following conditionis satisfied: (G12+G23)/EFL≦3 and/or EFL/G23≦100; and0.1≦(G12+G23)/EFL≦0.5 and/or 5.0≦EFL/G23≦11.0 may be defined in otherembodiments.

(4) From the foregoing, reduction of the thicknesses of the lenselements is an approach for achieving a shorter system length. However,the effective optical diameter of the fifth lens element 7 is relativelylarger, so that the reducible degree of T5 may be relatively smaller.The imaging lens 10 may have better performance if the followingcondition is satisfied: T1/T5≦7.0; and 0.5≦T1/T5≦1.2 may be defined inother embodiments.

(5) Since T3 is relatively thinner, G23 is relatively greater comparedto the rest of the air gap lengths. The imaging lens 10 may have abetter configuration if the following condition is satisfied:Gaa/G23≦30; and 2.5≦Gaa/G23≦5.0 may be defined in other embodiments.

However, in view of the unpredictability of the optical system design,under the framework of the present disclosure, conforming with theaforementioned conditions, the imaging lens 10 may have a shorter systemlength, a smaller F-number, a wider field-of-view, better imagingquality or enhanced assembly yield compared to the prior art.

To sum up, effects and advantages of the imaging lens 10 according tothe present disclosure are described hereinafter.

1) Cooperation of the concave portion 322 of the image-side surface 32and the aperture stop 2 disposed between the first lens element 3 andthe second lens element 4 may broaden the field of view of the imaginglens 10.

2) Light may be effectively focused by virtue of the convex portion 412and the convex portion 422. Imaging quality of the imaging lens 10 maybe enhanced by the cooperation between the convex portion 622 and theconcave portion 712. The plastic material of the third lens element 5may be helpful in reducing weight and manufacturing cost.

3) Through design of the relevant optical parameters, opticalaberrations, such as spherical aberration, may be reduced or eveneliminated. Further, through surface design and arrangement of the lenselements 3-7, even with the system length reduced, optical aberrationsmay still be reduced or even eliminated, resulting in relatively goodoptical performance.

4) Through the aforesaid six embodiments, it is known that the length ofthe imaging lens 10 of this disclosure may be reduced down to below 4.5mm while maintaining good optical performance.

Shown in FIG. 32 is a first exemplary application of the imaging lens10, in which the imaging lens 10 is disposed in a housing 11 of anelectronic apparatus 1 (such as a mobile phone, but not limitedthereto), and forms a part of an imaging module 12 of the electronicapparatus 1. The imaging module 12 includes a barrel 21 on which theimaging lens 10 is disposed, a holder unit 120 on which the barrel 21 isdisposed, and an image sensor 130 disposed at the image plane 100 (seeFIG. 6).

The holder unit 120 includes a first holder portion 121 in which thebarrel 21 is disposed, and a second holder portion 122 having a portioninterposed between the first holder portion 121 and the image sensor130. The barrel 21 and the first holder portion 121 of the holder unit120 extend along an axis (II), which coincides with the optical axis (I)of the imaging lens 10.

Shown in FIG. 33 is a second exemplary application of the imaging lens10. The differences between the first and second exemplary applicationsreside in that, in the second exemplary application, the holder unit 120is configured as a voice-coil motor (VCM), and the first holder portion121 includes an inner section 123 in which the barrel 21 is disposed, anouter section 124 that surrounds the inner section 123, a coil 125 thatis interposed between the inner and outer sections 123, 124, and amagnetic component 126 that is disposed between an outer side of thecoil 125 and an inner side of the outer section 124.

The inner section 123 and the barrel 21, together with the imaging lens10 therein, are movable with respect to the image sensor 130 along anaxis (III), which coincides with the optical axis (I) of the imaginglens 10. The optical filter 9 of the imaging lens 10 is disposed at thesecond holder portion 122, which is disposed to abut against the outersection 124. Configuration and arrangement of other components of theelectronic apparatus 1 in the second exemplary application are identicalto those in the first exemplary application, and hence will not bedescribed hereinafter for the sake of brevity.

By virtue of the imaging lens 10 of the present disclosure, theelectronic apparatus 1 in each of the exemplary applications may beconfigured to have a relatively reduced overall thickness with goodoptical and imaging performance, so as to reduce cost of materials, andsatisfy requirements of product miniaturization.

While the present invention has been described in connection with whatare considered the most practical embodiments, it is understood thatthis invention is not limited to the disclosed embodiments but isintended to cover various arrangements included within the spirit andscope of the broadest interpretation so as to encompass all suchmodifications and equivalent arrangements.

What is claimed is:
 1. An imaging lens comprising a first lens element,an aperture stop, a second lens element, a third lens element, a fourthlens element and a fifth lens element arranged in order from an objectside to an image side along an optical axis of said imaging lens, eachof said first lens element, said second lens element, said third lenselement, said fourth lens element and said fifth lens element having arefractive power, an object-side surface facing toward the object side,and an image-side surface facing toward the image side, wherein: saidfirst lens element has a negative refractive power, and said image-sidesurface of said first lens element has a concave portion in a vicinityof a periphery of said first lens element; said object-side surface ofsaid second lens element has a convex portion in a vicinity of aperiphery of said second lens element, and said image-side surface ofsaid second lens element has a convex portion in a vicinity of theperiphery of said second lens element; said third lens element is madeof a plastic material; said object-side surface of said fourth lenselement has a concave portion in a vicinity of the periphery of thefourth lens element, and said image-side surface of said fourth lenselement has a convex portion in a vicinity of a periphery of said fourthlens element; said object-side surface of said fifth lens element has aconcave portion in a vicinity of a periphery of said fifth lens element;and said imaging lens does not include any lens element with refractivepower other than said first lens element, said second lens element, saidthird lens element, said fourth lens element and said fifth lenselement, and satisfies 1.5≦(G12+G45)/T3≦5 and T3/G12≦1.1, where G12represents an air gap length between said first lens element and saidsecond lens element at the optical axis, G45 represents an air gaplength between said fourth lens element and said fifth lens element atthe optical axis, and T3 represents a thickness of said third lenselement at the optical axis, wherein an Abbe number of said first lenselement is smaller than an Abbe number of said fifth lens element. 2.The imaging lens as claimed in claim 1, further satisfying(G12+G23)/EFL≦3, where G23 represents an air gap length between saidsecond lens element and said third lens element at the optical axis, andEFL represents a system focal length of said imaging lens.
 3. Theimaging lens as claimed in claim 2, further satisfying T2/G23≦20, whereT2 represents a thickness of said second lens element at the opticalaxis.
 4. The imaging lens as claimed in claim 1, further satisfyingT1/T5≦7.0, where T1 represents a thickness of said first lens element atthe optical axis, and T5 represents a thickness of said fifth lenselement at the optical axis.
 5. The imaging lens as claimed in claim 4,further satisfying EFL/G23≦100, where EFL represents a system focallength of said imaging lens, and G23 represents an air gap lengthbetween said second lens element and said third lens element at theoptical axis.
 6. The imaging lens as claimed in claim 1, furthersatisfying T4/G23≦20, where T4 represents a thickness of said fourthlens element at the optical axis, and G23 represents an air gap lengthbetween said second lens element and said third lens element at theoptical axis.
 7. The imaging lens as claimed in claim 6, furthersatisfying 1.0≦ALT/Gaa≦3.0, where ALT represents a sum of thicknesses ofsaid first lens element, said second lens element, said third lenselement, said fourth lens element and said fifth lens element at theoptical axis, and Gaa represents a sum of four air gap lengths amongsaid first lens element, said second lens element, said third lenselement, said fourth lens element and said fifth lens element at theoptical axis.
 8. The imaging lens as claimed in claim 1, furthersatisfying T5/G23≦20, where G23 represents an air gap length betweensaid second lens element and said third lens element at the opticalaxis, and T5 represents a thickness of said fifth lens element at theoptical axis.
 9. The imaging lens as claimed in claim 8, furthersatisfying (G12+G34)/T3≦20, where G34 represents an air gap lengthbetween said third lens element and said fourth lens element at theoptical axis.
 10. The imaging lens as claimed in claim 1, furthersatisfying Gaa/G23≦30, where G23 represents an air gap length betweensaid second lens element and said third lens element at the opticalaxis, and Gaa represents a sum of four air gap lengths among said firstlens element, said second lens element, said third lens element, saidfourth lens element and said fifth lens element at the optical axis. 11.The imaging lens as claimed in claim 10, further satisfying0.4≦(G34+G45)/T1≦1.7, where G34 represents an air gap length betweensaid third lens element and said fourth lens element at the opticalaxis, and T1 represents a thickness of said first lens element at theoptical axis.
 12. The imaging lens as claimed in claim 1, furthersatisfying (G12+G45)/T5≦7, where T5 represents a thickness of said fifthlens element at the optical axis.
 13. The imaging lens as claimed inclaim 12, further satisfying ALT/G23≦60, where G23 represents an air gaplength between said second lens element and said third lens element atthe optical axis, and ALT represents a sum of thicknesses of said firstlens element, said second lens element, said third lens element, saidfourth lens element and said fifth lens element at the optical axis. 14.The imaging lens as claimed in claim 1, further satisfying T1/G45≦10,where T1 represents a thickness of said first lens element at theoptical axis.
 15. An electronic apparatus comprising: a housing; and animaging module disposed in said housing, and including an imaging lensas claimed in claim 1, a barrel on which said imaging lens is disposed,a holder unit on which said barrel is disposed, and an image sensordisposed at the image side of said imaging lens.